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RS-422 and Ethernet signals from the same connector?

Furkan Fehmi Sefiloglu
Expert 3118 points
Other Parts Discussed in Thread: TS3L110

Hi Team,

Can you please check and advise with following request?

"

We are considering a where we can receive both RS-422 and Ethernet signals from the same connector.

In this context, we need an IC that is compatible with the physical layer of both protocols that can switch RS-422 and Ethernet signals over itself and transmit them to the connector.

Is there an IC suitable for our needs among TI products?

Alternatively, if such a special purpose IC is not available, can you suggest an analog mux suitable for signal levels at the Ethernet and RS-422 physical layers?

"

Thanks in advance

Best Regards

Furkan Sefiloglu

  • 0
    TI__Genius 16030 points

    Hello Furkan,

    In ethernet PHYs we dont support RS-422.

    Regarding Ethernet signal levels : it will be 3.3V level signals with baud rate of 125MHz and rise/fall time of a few 100ps (assuming industrial Ethernet standards). You may have to check for muxes which can support these signals. I am not aware of muxes used in customer applications in the path of Ethernet signals.

    --

    Regards,

    Vikram

  • 0
    TI__Guru 52262 points

    Hi Furkan,

    I have a few questions - we may have a solution in an analog multiplexer but it really depends on the application specifics as these two areas are different niches w.r.t. to our switches.

    1. What are the ethernet speeds that are needed to be transferred in this application? (I.e. is it a 10Base-T,  etc) 

    2. What Frequency / Data Rate are you running the RS-422 at? 

    3. What power supplies are available in the system? (since RS-422 can be negative a dual sided switch will be best as none of our single supply switches will fit the range) 

    As a note - our typical LAN/Ethernet switch does not support teh RS-422, as it doesn't handle negative voltages so I am looking to see if the ethernet speeds and available supplies we can swing one of our dual supply precision parts to support both protocols - so please let me know and  I will see what we can do!

    Best,

    Parker S. Dodson

  • 0 in reply to Parker Dodson
    TI__Expert 3118 points

    Hi Parker,

    Can you please check and advise with following?

    "

    Ethernet will be 100Base-T and RS-422 communication max. It will be done at 230400 Baud rate.

    Power supplies in the system are limited to 3.3V and 5V provided for RS422 phy and Ethernet phy and are single supply voltages.

    I had the opportunity to examine the TI product TS3L110, which we thought we could use for both protocols.

    We would like to get your approval on its usability, especially since it has high bandwidth and RS-422 and Ethernet signals are close to each other in the physical layer.

    Also, if there are other products you can recommend, we can review them.

    "

    Thanks in advance

    Best Regards

    Furkan Sefiloglu

  • +1 in reply to Furkan Fehmi Sefiloglu
    TI__Guru 52262 points

    Hi Furkan,

    The TS3L110 should work fine for 100Base-T and the RS422 phy at that Baud Rate. Using a 3.3V supply will work as the part can pass 0V to 5V signals without problem at a 3.3V supply.  I think this is our best option for the application. The switch doesn't really care about protocol since its essentially an analog FET switch (this device specifically is a charge pump + NFET switch - you can tell because it has a flat on resistance response and it can pass above supply voltage) - so it really won't notice too much of a difference between protocols as each of the signal ranges are within operating specs  and the bandwidth should be okay (as the TS3L110 has a nominal BW of 500MHz per channel so it should be good on that front as well). 

    If you have any other questions please let me know!